Kellie Pickler shaved her head live on Good Morning America yesterday. The shocking move was a show of solidarity with her life-long friend who was recently treated for breast cancer. Kellie refers to Summer Holt Miller as her "sister", and has stood beside her throughout her breast cancer prognosis and subsequent treatment since receiving word of the diagnosis in June of this year.  Summer also shaved her head as a means of bringing awareness to the importance of early detection.  Summer was just 36 years old when she received word of her diagnosis.  Kellie said, "Cancer does not discriminate. If this compels even one person to change their mentality toward waiting until the age of 40 for their mammogram, then it will be worth it."   Summer, a mother of two, recently underwent a double mastectomy and will begin chemotherapy today.   A behind-the-scenes video capturing the ladies' cuts and truthful candor about Summer's diagnosis and treatment will be shared on Athena Water's website, www.athenawater.com, and Athena will make a monetary donation to the American Cancer Society in Summer's honor. Athena will contribute a minimum of $2 million to support breast cancer awareness, care, education and research by 2014.